1. Technical Field
The invention relates to the use of a phosphodiesterase type III (PDE III) inhibitor or a “Ca2+-sensitizing agent” or a pharmaceutically acceptable derivative thereof for the preparation of a medication for the reduction of the heart size of a patient suffering from heart failure.
2. Background Information
Intravenous positive inotropic agents play a vital role in the management of acute heart failure, and will often result in a short-term improvement in dogs with dilated cardiomyopathy (DCM). Many dogs with DCM have a very guarded prognosis (Monnet et al., 1995), with Dobermanns in particular generally experiencing only short survival times (Calvert et al., 1982; Calvert et al., 1997). There have been few studies examining the influence of treatment on survival in dogs with DCM, although a subanalysis of the dogs with DCM in the LIVE study showed an improvement in time to treatment failure in those dogs receiving enalapril compared with placebo (142.8 versus 56.5 days, respectively) (Ettinger et al., 1998). On the whole, oral positive inotropic agents have lost favour in the treatment of chronic heart failure in human patients in recent years, after a number of trials revealed adverse effects on survival despite short-term hemodynamic benefits (Packer et al., 1991; Cowley and Skene, 1994). Recently it has been suggested that calcium sensitising agents may result in positive inotropic effects without producing some of the adverse effects (including calcium overload) associated with more traditional positive inotropes such as dobutamine, aminone and milrinone.
Pimobendan is an inodilator compound with calcium sensitising effects, as well as some phosphodiesterase type III inhibitory effects. Rather than increasing calcium entry into cardiac myocytes, calcium sensitisers achieve their positive inotropic effect by sensitising the contractile proteins to existing cytosolic calcium, by altering the binding of calcium with troponin-C. Producing a positive inotropic effect by calcium sensitising thereby avoids some of the adverse effects of cytosolic calcium overload. Increased cytosolic calcium levels have been associated with an increased tendency for arrhythmias and sudden death. Clinical trials of long-term use of oral pimobendan in human patients with heart failure have demonstrated an improvement in exercise tolerance and quality of life without significantly adverse effects on survival (Kubo et al., 1992; Katz et al., 1992).
It is known that the progress of heart failure is associated with an increase of the size of the heart. In dilated cardiomyopathy (DCM) the ratio of left ventricular wall thickness to chamber diameter is decreased and the circumferences of the annuluses of the mitral and tricuspid valves are increased in proportion to the magnitude of chamber dilation. DCM may either be caused primarily by e.g. genetic abnormalities are secondarily e.g. due to valvular insufficiency both resulting in cardiac volume overload. However, it involves usually cardiac remodeling that may be defined as genome expression, molecular, cellular, and interstitial changes manifested clinically as changes in size, shape, and function of the heart. Cardiac remodelling is generally an adverse sign and linked to heart failure progression. Reverse cardiac remodelling is a goal of the treatment of heart failure therapy.
Heart failure therapy has traditionally focussed largely on symptomatic relief rather than on addressing underlying disease problems.
The problem underlying the present invention was to provide a medication, which allows to remodel the size of the heart to reduce the risk of death in patients with coronary diseases. In particular, the problem underlying the present invention was to provide a medication, which facilitates the reduction in size of the heart to reduce the risk of death in patients suffering from heart failure.